1. Field of the Invention
The present invention relates generally to a method and apparatus for the delivery of flat products, and more particularly, to a method and apparatus for the delivery of flat products which are to be folded during delivery in a printing press.
2. State of the Art
Conventional printing presses include devices for delivering flat printed products from one stage of the press to another. For example, a web of flat material which has been sliced along its length into multiple ribbons, is typically transported to a location where the ribbons are subsequently cut along their width into signatures. The signatures are then folded one or more times to form the multiple pages of, for example, a magazine or newspaper. A typical newspaper folder may receive a collection of ribbons which have already been previously folded one or more times, and be required to implement an additional fold, such as a half fold. The number of pages which the newspaper folder is required to fold can vary widely up to, on the order of 100 broadsheet pages or more. The devices used to implement these folds include jaw folders and rotary tucker blade folders.
Jaw folders, such as jaw folders which use a jaw to interface with a fixed tucker blade, have the advantage of providing a relatively accurate, mark-free cross-fold, such as an accurate half fold. However, jaw folders are constrained in the number of pages which they can fold due to limited engagement of tucker blades and jaws used to implement the folds, as well as by the space between the tucker blade and jaw cylinders. For example, typical jaw folders are limited to folding 64 pages or less.
Rotary tucker blade folders which use a rotating cylinder having either fixed or retractable tucker blades, can accommodate a large range of paging when implementing a fold. However, rotary tucker blade folders are less accurate than jaw folders, and create more marking on the printed product.
Thus, the newspaper folders used in conventional printing presses have resulted in the accurate folding of only a limited number of pages, or have resulted in folding a larger number of pages with less accuracy. Accordingly, it would be desirable to provide a newspaper folder which can provide the accuracy and absence of marking associated with a jaw folder, without being subject to the maximum paging range typically associated with a jaw folder. Further, it would be desirable to achieve such advantages in a relatively simple configuration which can provide positive and accurate delivery of a folded product, using for example, a gripping transport device.
Although gripping transport devices are available, these devices have not been suitable for transporting folded product of, for example, a printing press used in printing newspaper. For example, U.S. Pat. No. 4,132,403, U.S. Pat. No. 4,290,595, U.S. Pat. No. 4,629,175, U.S. Pat. No. 4,767,112, U.S. Pat. No. 4,629,175, U.S. Pat. No. 5,452,886 and U.S. Pat. No. 5,560,599 disclose the use of gripping elements associated with a rotatable gripper drum for grasping a product and transporting the product to a second location. Further, these patents disclose that during transport, the product can be decelerated from a first speed to a second speed. In addition, in co-pending U.S. application Ser. No. 08/707,518, entitled "Method and Apparatus For Conveying Flat Printed Products", a conveying device for flat printed products is disclosed which includes plural arms, each having a seizing device for seizing signatures emerging from a transport device.
However, the foregoing documents do not address the inability of conventional folders to provide accurate, mark-free folding of a wide maximum paging range, or the transport of folded products from such a folder to a downstream location of a printing press.